import java.util.HashSet;
import java.util.Objects;
import java.util.Set;

class Student{
    private String name;
    private  int age;

    public Student(String name, int age) {
        this.name = name;
        this.age = age;
    }

    @Override
    public String toString() {
        return "Student{" +
                "name='" + name + '\'' +
                ", age=" + age +
                '}';
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        Student student = (Student) o;
        return age == student.age && Objects.equals(name, student.name);
    }

    @Override
    public int hashCode() {
        return Objects.hash(name, age);
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }
}
public class Test {
    public static void main(String[] args) {
        Set<Student> students=new HashSet<>();
        Student stu1=new Student("张三",20);
        Student stu3=new Student("张三",20);
        Student stu2=new Student("李四",21);
        Student stu4=new Student("李四",21);
        students.add(stu1);
       students.add(stu2);
       students.add(stu3);
       students.add(stu4);
       System.out.println(students);
    }
}
